1. Field of the Invention
This invention relates to a sheet discharging apparatus and a sheet treating apparatus provided with the same.
2. Description of Related Art
Among image forming apparatuses such as a digital copying machine, a printer and a facsimile apparatus, there is one provided with an image forming portion and an image reading apparatus for reading an original, and adapted to form an image on the basis of image information read by this image reading apparatus.
The image reading apparatus provided in such a conventional image forming apparatus, or an image reading apparatus as a unit is provided with an automatic original feeder for continuously feeding originals which is an example of a sheet discharging apparatus. As such an automatic original feeder (automatic document feeder: ADF), there have been proposed various ones provided with the function of separating and feeding a plurality of originals placed on an original plate (platen) one by one and conveying them to an image reading portion, and further reversing and discharging the originals.
Now, an original image reading method in the image reading apparatus provided with such an automatic original feeder is divided broadly into a fixed reading method of placing an original on an original plate, and optically reading image information while moving image reading means, and a flow reading method of fixing image reading means at a predetermined location on an original plate, and optically reading image information while conveying an original.
In recent years, chiefly the flow reading method has been adopted from such advantages as an improvement in productivity such as the treating capacity within a predetermined time, and the downsizing of the apparatus. In the case of this flow reading method, a reversal path for copying with a both-side original can also be minimized.
In such a conventional ADF 180, however, particularly when the rigidity of an original P which is a sheet is small, in other words, when the stiffness of the original P is weak, there is a case where when it passes between a pair of discharging rollers 16 in a spaced-apart state, as shown in FIG. 9 of the accompanying drawings, the leading edge portion of the original leans on a discharging tray 19 and becomes rounded on the discharging tray 19, thus causing jam.
So, heretofore, as a countermeasure for this, as shown in FIG. 10 of the accompanying drawings, a rib 55 for heightening the rigidity of the original P has been provided on a sheet discharging lower guide 51a (see Japanese Patent Application Laid-Open No. 2002-226114). The jam of the original P caused by the original P becoming rounded on the discharging tray 19 is prevented by the rigidity of the original P being enhanced by the rib 55.
In such a conventional ADF 280 and an image reading apparatus provided with the same, however, when the rigidity of the original P is thus heightened by the rib 55, the jam of the original P can be prevented, but the trailing edge portion of the original P is also heightened in rigidity. Therefore, when the trailing edge of the original P is kicked out by the pair of discharging rollers 16 now in contact with each other and the sheet is discharged onto the discharging tray, the original P jumps excessively due to being heightened in rigidity, thus causing faulty alignment in a direction in which the sheet is discharged. Also, when it jumps excessively, the original P may sometimes fall from the discharging tray 19.